Method and apparatus for selectively omitting video frames during playback

Abstract

In a method and apparatus for decompressing with a video decompressor a compressed digital video signal representative of an input sequence of digital video frames, the processing power associated with the video decompressor is determined, and a decompression threshold value is selected from a plurality of candidate decompression threshold values in accordance with the processing power associated with the video decompressor. The video decompressor generates a decompressed digital video output signal in response to the compressed digital video signal, and the decompressed digital video output signal is monitored to determine whether the video decompressor is timely generating an output sequence of decompressed digital video frames. Compressed digital video frames are omitted from the compressed digital video signal provided to the video decompressor in response to the monitoring and in accordance with the decompression threshold.

What is claimed is: 
     
       1. A method for forming a decompressed digital video output signal with a video decompressor from a compressed digital video signal representative of an input sequence of digital video frames, comprising the steps of: (A) determining the processing power associated with said video decompressor, said processing power related to a rate of processing data;   (B) selecting a decompression threshold value from a plurality of candidate decompression threshold values in accordance with said processing power associated with said video decompressor;   (C) generating with said video decompressor said decompressed digital video output signal in response to said compressed digital video signal;   (D) monitoring said decompressed digital video output signal to determine whether said video decompressor is timely generating an output sequence of decompressed digital video frames; and   (E) omitting compressed digital video frames from said compressed digital video signal provided to said video decompressor in response to said monitoring step and in accordance with said decompression threshold.   
     
     
       2. The method of claim 1, wherein step (E) further comprises the steps of: (i) generating a frames missed value in response to said omitted frames;   (ii) monitoring deviations in said frames missed value; and   (iii) selectively adjusting downward a target decompression rate associated with said video decompressor in accordance with said deviations in said frames missed value.   
     
     
       3. The method of claim 2, wherein step (E)(ii) comprises the steps of: a. storing a plurality of frames missed values; and   b. determining a variance value in accordance with a statistical variance of said plurality of frames missed values.   
     
     
       4. The method of claim 3, wherein step (E)(iii) comprises the steps of: i. comparing said variance value to said decompressor threshold; and   ii. if said variance value exceeds said decompression threshold, then adjusting downward said target decompression rate.   
     
     
       5. The method of claim 4, wherein said target decompression rate is repeatedly adjusted downward until said variance value does not exceed said decompression threshold. 
     
     
       6. The method of claim 1, wherein said input sequence of digital video frames has a sequence of audio frames associated therewith, wherein step (D) comprises the step of monitoring said decompressed digital video output signal to determine whether said decompressed digital video output signal is lagging in time behind an audio decompressor output signal. 
     
     
       7. An apparatus for forming a decompressed digital video output signal with a video decompressor from a compressed digital video signal representative of an input sequence of digital video frames, comprising: (A) sensing means for determining the processing power associated with said video decompressor, said processing power related to a rate of processing data;   (B) a threshold selector for selecting a decompression threshold value from a plurality of candidate decompression threshold values in accordance with said processing power associated with said video decompressor;   (C) said video decompressor including means for generating said decompressed digital video output signal in response to said compressed digital video signal;   (D) means for monitoring said decompressed digital video output signal to determine whether said video compressor is timely generating an output sequence of decompressed digital video frames; and   (E) means for omitting compressed digital video frames from said compressed digital video signal provided to said video decompressor in response to said monitoring step and in accordance with said decompression threshold.   
     
     
       8. The apparatus of claim 7, wherein said means for omitting compressed digital video frames further comprises: (i) means for generating a frames missed value in response to said omitted frames;   (ii) means for monitoring deviations in said frames missed value; and   (iii) target decompression rate adjustment means for selectively adjusting downward a target decompression rate associated with said video decompressor in accordance with said deviations in said frames missed value.   
     
     
       9. The apparatus of claim 8, wherein said means for monitoring deviations in said frames missed value comprises: a. means for storing a plurality of frames missed values; and   b. means for determining a variance value in accordance with a statistical variance of said plurality of frames missed values.   
     
     
       10. The apparatus of claim 9, wherein said target decompression rate adjustment means comprises: i. a comparator for comparing said variance value to said decompressor threshold; and   ii. means for adjusting downward said target decompression rate if said variance value exceeds said decompression threshold.   
     
     
       11. The apparatus of claim 10, wherein said target decompression rate is repeatedly adjusted downward by said target decompression rate adjustment means until said variance value does not exceed said decompression threshold. 
     
     
       12. The apparatus of claim 7, wherein said input sequence of digital video frames has a sequence of audio frames associated therewith, wherein said means for monitoring said decompressed digital video output signal comprises means for monitoring said decompressed digital video output signal to determine whether said decompressed digital video output signal is lagging in time behind an audio decompressor output signal.